Aerobic and anaerobic bioremediation of contaminated soils, ground water sites, lakes, ponds, aquifers, wells, shore fronts, oceans and the like have proven effective in remediating toxic organic and inorganic compounds such as fuel oil, gasoline, PCBs, DDT, and other pesticides, and the like. Bioremediation projects that have been successfully implemented are in areas that include underground storage tank spills and leakages; hazardous solid wastes; ground spills; and contamination of ground water (wells), geological aquifers and the like. Aerobic and anaerobic bioremediation have proven to be more cost effective and timely than conventional engineering technologies, and have the further advantage in that they do not produce wastes which enter the surrounding air, water and soils. Anaerobic bioremediation has been shown to be the most effective and least expensive method of remediation of toxic materials. Other remediation technologies such as standard physical soil and ground-water remediation ie. excavation and disposal or pump and treat systems and soil-vapor extraction (SVE) remediation which have all been shown to be moderately high in capital costs; require long-term operation and maintenance including labor, materials and power consumption; time parameters that are in months to years; and remediation effectiveness results being moderately low in the cleaning-up of the contaminated soils and ground water. These remediation techniques are also limited by considerations of depth of soil to be removed; obstructions in the geologic formations; safety conditions at the site; and environmental law statutes with regard to Federal, State and local regulatory agencies for a site remediation project that produces wastes that effect air, water and soil conditions. These aforementioned remediation technologies generally are less feasible, and significantly more expensive and sometimes prohibitive in terms of logistics and/or overall costs.
Problems associated with anaerobic bioremediation have included the difficulty of achieving significant increases in the naturally occurring indigenous microorganisms at the contaminated site using appropriate chemical compositions of nutrients that would successfully have the indigenous anaerobic bacteria metabolize the organic and inorganic contaminants. The inability to maximize the rate of metabolism of toxic contaminants by anaerobic microorganisms can be due to inadequate or incorrect electron acceptors, nutrient forms of nitrogen and phosphorus, trace-mineral micronutrients, chelating agents, non-toxic surfactants, lack of carbon co-substrates, and inerting agents. There is also a physical inability to deliver, distribute and disperse the nutrients readily, rapidly and over a wide distribution area within the contaminated geologic media for effective biodegradation of the contaminated substances into non-toxic end-products. Also, there is a difficulty of working with anaerobic microorganisms and processes because the biochemical pathways describing the anaerobic degradation of organic and inorganic compounds have been difficult to characterize, and to a large degree, are yet to be fully understood. Thus, it can be seen that anaerobic bioremediation of contaminated geologic media such as ground water (wells), sludge, soil and the like is not an easy or simple technological problem.
There remains a need for an improved method and apparatus for the anaerobic bioremediation of organic and inorganic toxic compounds within a contaminated geologic media to form non-toxic end products without further formation of waste by-products that effect air, water and soil qualities at the geologic site. In addition, there is a need that the bioremediation be accomplished by having an in-situ treatment of the contaminated geologic media such that the organic and inorganic contaminants are metabolized or transformed by naturally occurring indigenous, denitrifying and/or manganese-, iron- and sulfate-reducing anaerobic microorganisms using the aforementioned electron acceptors, in combination with nutrients, surfactants, chelating agents, a diluent, and an inert gas to convert the contaminants within the contaminated geologic media into non-toxic end products. These naturally occurring indigenous microorganisms which operate using one or more respiration pathways are hereafter called "multiple respiration pathway" (MRP) microorganisms.